The present invention relates to a fat composition of excellent cold-resistance by inhibiting crystal growth of the fat even for long-term storage at a low temperature (in a refrigeration or freezing temperature range).
Some fats, even if they are in a liquid state at room temperature, come to lose fluidity at low temperatures in the refrigeration or freezing temperature range of 0xc2x0 C. to xe2x88x9220xc2x0 C. and then solidify. However, of vegetable oils, special vegetable oils such as evening primrose seed oil, kukuinut seed oil and tobacco seed oil do not solidify even at xe2x88x9220xc2x0 C. However, the amounts of supply thereof are few and the prices are also expensive, and thus they are not utilized in large quantities. Castor oil, rapeseed oil, macadamia oil, etc. are liquid at room temperature, the amounts of supply thereof are not few, and the prices are not expensive, and so they seem to be used in high volume. However, they come to lack fluidity in the freezing temperature range of xe2x88x9220xc2x0 C. and solidify.
Conventionally, as techniques for solving the problem of these vegetable oils solidifying at low temperatures, JP 5-209187 A proposes a cold-resistant vegetable oil obtained by adding to a vegetable oil three components of a polyglycerol fatty ester, a sucrose fatty ester and lecithin. JP 8-239684 A proposes a cold resistance improved fat composition prepared by adding a vegetable oil having a solid fat content at a temperature of 10xc2x0 C. of 10% or less to a specific amount of a sucrose fatty ester having a HLB of 3 or less. JP 9-310088 A proposes an anti-crystallization agent for edible liquid fats comprising a mixture of a polyglycerol fatty acid and a sorbitan fatty ester. However, these technologies are still unsatisfactory.
The objects of the present invention are to provide a fat composition of excellent cold-resistance by inhibiting crystal growth of the fat even in long-term storage at a low temperature (in a refrigeration or freezing temperature range) and also to provide a process of producing the fat composition.
The present inventors have studies intensively in order to solve the above problem and, as a result, they have found that it is possible to provide a cold-resistant fat composition comprising 0.15 to 4.5% by weight of tri-saturated fatty acid glycerides based on a fat which is in a liquid state at room temperature and has 60% or more of the proportion of polyunsaturated fatty acids in all the unsaturated fatty acids therein, as well as a process for producing thereof and an oil-based food comprising as a main component of its fat component(s) the cold-resistant fat composition.
As the fat used in the present invention, a liquid fat at room temperature is preferred. Raw materials thereof include, for example, vegetable fats such as rapeseed oil, soybean oil, sunflower seed oil, cottonseed oil, peanut oil, rice bran oil, corn oil, safflower oil, olive oil, kapok oil, sesame oil, evening primrose oil, palm oil, and palm kernel oil, as well as processed fats thereof prepared by subjecting these fats to hydrogenation, fractionation, interesterification, etc.
Fats are composed of fatty acids and glycerin and, of constituent fatty acids of fats, those whose carbon-carbon links are only single bonds are referred to as saturated fatty acids, and examples thereof include caprylic acid, n-capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, lignoceric acid and the like. Further, of fatty acids, those having one or more double bonds in carbon-carbon links are referred to as unsaturated fatty acids and examples thereof include oleic acid, linoleic acid and linolenic acid. Of unsaturated fatty acids, those having two or more double bonds are particularly referred to as polyunsaturated fatty acids.
In the present invention, it is required to use a fat which is liquid at room temperature of 15xc2x0 C. to 25xc2x0 C. and whose proportion of polyunsaturated fatty acids to all the unsaturated fatty acids is 60% or more. Fats whose proportion of polyunsaturated fatty acids to all the unsaturated fatty acids is less than 60% are completely solidified when they are allowed to stand at xe2x88x9220xc2x0 C. for 24 hours. Then, in case of these fats, fats are completely solidified because the amount of fat crystals is too large during storage in a freezing temperature range.
The tri-saturated fatty acid glycerides used in the present invention are triglycerides all whose constituent fatty acids are saturated fatty acids. Preferred saturated fatty acids include myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, and lignoceric acid. Examples thereof include those of extremely hydrogenated oil of high erucic acid rapeseed oil, extremely hydrogenated oil of palm oil, extremely hydrogenated oil of rice bran oil and the like. The method for addition of the tri-saturated fatty acid triglycerides to the fat in the present invention is not specifically limited. The amount to be added is 0.15 to 4.5% by weight, preferably 0.3 to 3.0% by weight. When the amount to be added is below the lower limit, the effect is recognized to some extent, but insufficient. When the amount exceeds the upper limit, the effect is recognized, but insufficient and meltability in the mouth becomes bad. As long as the above formulation ratio is met, other emulsifier(s) for foods (e.g. polyglycerol fatty acid ester, sucrose fatty acid ester, lecithin, etc.) may be used in combination.
The cold-resistant fat of the present invention can be used as a coating fat for frozen foods, a mold lubricant, an oil-based sauce, and oil-based foods such as a dressing to be used at a low temperature. The fat can also be used as a lubricant oil for machinery utilized in other different fields. For example, a method for producing a fat for coating and a mold lubricant can be carried out by incorporating tri-saturated fatty acid glycerides into a fat which is in a liquid state at room temperature and has 60% or more of the proportion of polyunsaturated fatty acids in all the unsaturated fatty acids therein in an amount of 0.15 to 4.5% by weight based on the fat, mixing and melting the resultant mixture and cooling the mixture to obtain the desired product. In addition, a method for producing an oil-based sauce can be carried out by mixing and melting the above cold-resistant fat composition, saccharides, a solid flavor material and an emulsifier, and then cooling the resultant mixture to obtain the desired product. Examples of saccharides include sucrose, maltose, glucose, powdered wheat gluten, fructose, lactose, trehalose, powdered maltose, etc. Examples of solid flavor materials include dairy products such as a whole milk powder, a skim milk powder, a cream powder, a whey powder, a butter milk powder, etc., cacao components such as cocoa powder, an adjusted cocoa powder, etc., a cheese powder, a coffee powder, a fruit juice powder, etc. By using the cold-resistant fat component of the present invention as a main component of a fat component of these oil-based foods, the crystal growth of the fat is inhibited even at long-term storage at a low temperature (in a refrigeration or freezing temperature range), thereby maintaining the fluidity of these oil-based foods.